1. Field of the Invention
The present invention relates generally to a system for orienting and guiding a mobile robot. More particularly, the invention pertains to apparatus utilizing both ultrasonic and infrared sensors to derive data for a software process that enables the robot to "see" sufficiently well to navigate by itself while avoiding obstacles in its path.
2. Discussion of the Prior Art
In my U.S. Pat. No. 4,638,445, issued Jan. 20, 1987, whose entire disclosure is incorporated herein by reference thereto, there is described an autonomous mobile robot employing a vision system having two arrays of ultrasonic sensors for obtaining data on the position and distance of objects in the workspace. One of the sensor arrays is used principally to see near objects and the other array is used principally to see far objects. The two arrays, preferably, are symmetrically disposed about an axis that extends through the body of the robot. This enables the robot to see in all directions of the workspace without having to spin around to collect data, while enabling the robot to turn about its axis of symmetry should such motions be desired. By having the arrays symmetrically disposed about the axis of symmetry extending through the robot's body, a computer, carried on board the robot (and not shown in the drawing so as not to obfuscate the invention), is relieved of the task of having to manipulate the data to simulate that arrangement. In the arrangement described in my aforesaid patent, the sensors, preferably, are cyclically polled in a repetitive sequence; but the cycle or the sequence, or both, with some increase in software complexity, may be altered to deal with special situations. Data received from the sensors is stored and provides a continually updated representation of the space and objects seen by the sensors. A software program causes the computer to utilize the data provided by the sensors to control the robot so as to enable the robot to navigate by itself while avoiding collisions with obstacles in its path and enabling the robot to take a different path when required, to get around obstacles blocking its movement.
The invention disclosed herein enables the robot to navigate with greater precision than can be attained with the coarse resolution provided by the prior ultrasonic vision systems and enables the robot to utilize a higher rate of data acquisition by substantially reducing crosstalk between the transducers of the ultrasonic vision systems.